Sintered metal commutator



July'6, 1965 w. HOVEN SINTERED METAL comumon 2 Sheets-Sheet 1 Filed Nov. 14, 1962 FIG. 2

WILHELM HOVE N 1N VEN TOR w. HOVEN SINTERED METAL coMMuTA'rdR July 6, 1965 Filed Nov. 14, 1962 2 Sheets-Sheet 2 WILHELM HOVEN INVENTOR.

United States Patent 3,193,714 SINTERED METAL COMMUTATOR Wiihelm Hoven, Wurselen, Germany, assignor to Garhe,

Lahmeyer & C0., A.G., Aachen, Germany, a corporation of Germany Filed Nov. 14, 1962, Ser. No. 237,585 Claims priority, application Germany, Nov. 14, 1961,

33,583 2 Claims. (Cl. 310-436) This invention relates to a sintered metal commutator and, more particularly, to the portion of an electric motor or generator contacted by brushes for transmission of electricity formed ofpowdered metal.

Motor and generator commutators are formed of a plurality of segmental copper bars arranged in a cylindrical form with insulation between adjacent bars. Because these bars require accurate sizing, they are conventionally finished by machining operationsand they are, therefore, very expensive because of the cost of the skilled labor and machine tools that must be used. It has been suggested that these bars be formed of pressed .and sintered powdered metal, but attempt-s to do so have not been successful because of the peculiar shape and arrangement of the bars. The space between adjacent bars is very small, so that it is impossible to make a pressing die that is strong enough to resist the extreme pressures used in powdered metal technology. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a commutator formed inexpensively and accurately from powdered metal.

Another object of this invention is the provision of a sintered metal commutator formed in two parts in pressure dies capable of resisting extreme pressing forces.

A further object of the present invention is the prO- vision of a commutator manufactured in two parts, wherein some of the bars are formed in one of the parts and the remainder of the bars are formed in the other of the parts.

It is another object of the instant invention to provide a commutator which is formed of pressed and sintered powdered metal, whereby it is light in weight, has a high strength-to-weight ratio, and can be made quickly and inexpensively to close tolerances on dimension.

With these and other objects in view, as will be apparent to those skilled in the art, the invention reside in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings in which:

FIG. 1 is a perspective view, in partially assembled form, of a commutator embodying the principles of the present invention,

FIG. 2 is a perspective view of the invention in completely disassembled condition,

FIG. 3 is an end view of a part of the invention,

FIG. 4 is a side view of the part,

FIG. 5 is a side view of another part of the invention,

FIG. 6 is an end view of the part shown in FIG. 5,

FIG. 7 is a side view of the completely assembled invention, and

FIG. 8 is an end view of the assembled invention.

Referring first to FIGS. 1 and 2, wherein are best shown the general features of the invention, the commutator, indicated generally by the reference numeral 10, consists of a first part 11 and a second part 12. The first part comprises a plurality of bars 13 extending parallel to one another and arranged spaced from one another in a circle. At one end, the group of bars is joined together and held in this relationship by an annular ring 14. At the other 3,193,714 Patented July 6, 1965 ice end, each bar is providedwith a radially-extending abutment 15. In a similar way, the second part 12 is provided with a plurality of bars 16 arranged in a circle in parallel, spaced relationship. The bars 16 are held in this condition by a ring 17. 'At the point where each bar joins the ring, the bar is provided with an abutment 18 in the nature of part of the ring 17. Between each pair of abutments 18, the ring is provided with a recess 19 capable of receiving the end of a bar 13 and its abutment 15.

An examination of the two parts 11 and 12 will show that they can be readily formed from powdered metal. Both are capable of being formed of a mixture of powdered metal and binding compound in a strong simple die in a pressing machine. After pressing, each part is sub jected to a conventional sintering process in a furnace in which the binding compound is removed and a strong, porous metal article remains.

As is evident in FIGS. 3 and 4, each of the bars 13 is provided with radially-extending side surfaces and the abutments 15 continue this wedge-shaped cross-section.

An examination of FIGS. 5 and 6, shows that the bars 16 of the second part 12 have the same cross-sectional shape as the bars 13 of the first part 11. The abutments 18 of the bars 16 are joined only by thin webs formed by the ring 17, the recesses 19 constituting slots or spaces between the abutments and the ring.

FIGS. 7 and 8 show the assembled commutator after the interleaving operation (indicated in FIG. 1) has been completed. The abutments 15 of the first part 11 reside in the recesses 19 of the second part 12. To complete the commutator, strips of insulation are inserted radially between the adjacent surfaces of the alternately-located bars 13 and 16; this serves to lock the assemblage together by frictional engagement. Then, the rings 14 and 17 are removed by turning in a lathe, or by a similar operation. The removal of the rings leaves the bars in an independent condition electrically, but locked together mechanically by the insulation. In assembling the commutator in a motor or generator, the end bearing the abutments 15 and 18 will be mounted adjacent the end of the rotor and will be electrically and mechanically connected to the rest of the electrical device. It is evident that the rings 14 and 17 may be left in place until the commutator has been assembled in the electrical device.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, de* sired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. A commutator, comprising:

(a) a first part consisting of a plurality of bars arranged in spaced, parallel relationship and connected by a ring, and

(b) a second part consisting of a plurality of bars ar ranged in spaced, parallel relationship and connected by a ring and interfitted with the bars of the first part to form an assembly, the said parts being made of pressed and sintered powdered metal, the ends of the bars of the first part being provided with outwardly extending abutments at the end away from its ring and the bars of the second part being provided with similar abutments adjacent its ring, the abutments being interfifitted to bring about peripheral alignment to define an outwardly-extending flange for incorporation into a rotary electrical device.

2. A method of manufacturing a commutator, comprising the steps of forming a first and a second part from pressed and sintered powdered metal, each part being integrally formed as a plurality of parallel, spaced bars joined by a ring, of assembling the first and second part so that the bars are interfitted and peripherally aligned, of inserting insulation between adjacent bars and locking the two parts together, and of then removing the rings by a machining process.

References Cited by the Examiner UNITED STATES PATENTS 1,545,673 7/25 McCarty 310183 41 2,456,779 12/48 Goetzel. 2,672,564 3/54- Krasno 310-236 2,997,777 8/61 Davies 29182 5 FOREIGN PATENTS 1,032,383 6/58 Germany. 160,568 9/57 Sweden.

ORIS L. RADER, Primary Examiner. MILTON o. HIRSHFIELD, Examiner. 

1. A COMMUTATOR, COMPRISING: (A) A FIRST PART CONSISTING OF A PLURALITY OF BARS ARRANGED IN SPACED, PARALLEL RELATIONSHIP AND CONNECTED BY A RING, AND (B) A SECOND PART CONSISTING OF A PLURALITY OF BARS ARRANGED IN SPACED, PARALLEL RELATIONSHIP AND CONNECTED BY A RING AND INTERFITTED WITH THE BARS OF THE FIRST PART TO FORM AN ASSEMBLY, THE SAID PARTS BEING MADE OF PRESSED AND SINTERED POWDERED METAL, THE ENDS OF THE BARS OF THE FIRST PART BEING PROVIDED WITH OUTWARDLYEXTENDING ABUTMENTS AT THE END AWAY FROM ITS RING AND THE BARS OF THE SECOND PART BEING PROVIDED WITH SIMILAR ABUTMENTS ADJACENT ITS RING, THE ABUTMENTS BEING INTERFITTED TO BRING ABOUT PERIPHERAL ALIGNMENT TO DEFINE AN OUTWARDLY-EXTENDING FLANGE FOR INCORPORATION INTO A ROTARY ELECTRICAL DEVICE. 